Measurement of the top quark mass in the tt¯→dilepton channel from √s=8 TeV ATLAS data

Abstract

The top quark mass is measured in the tt¯ → dilepton channel (lepton = e, µ) using ATLAS data recorded in the year 2012 at the LHC. The data were taken at a proton–proton centre-of-mass energy of √s = 8 TeV and correspond to an integrated luminosity of about 20.2 fb−1. Exploiting the template method, and using the distribution of invariant masses of lepton–b-jet pairs, the top quark mass is measured to be mtop = 172.99 ± 0.41 (stat) ± 0.74 (syst) GeV, with a total uncertainty of 0.84 GeV. Finally, a combination with previous ATLAS mtop measurements from √s = 7 TeV data in the tt¯ → dilepton and tt¯ → lepton+jets channels results in mtop = 172.84 ±0.34 (stat) ±0.61 (syst) GeV, with a total uncertainty of 0.70 GeV.